1. Field of the Invention
The present invention relates to: an inclination detector used in apparatuses and devices that require accurate inclination angle detection such as a laser marker, a surveying device, and a measuring device; and to a laser marker using the same.
2. Description of the Related Art
Some apparatuses and devices that require accurate inclination angle detection such as a laser marker, a surveying device, and a measuring device, allow an inclination thereof to be corrected through adjustment including inclination angle detection, and manual operation or automatic control. To adjust and control an inclination of a device accurately, an inclination of the device needs to be accurately detected. Inclination angle detectors are available that use: bubbles; or an electric resistance of an electrolytic solution.
In the inclination detector using bubbles, a light beam is projected from a light source disposed at one side and a light sensor disposed at the other side across a bubble tube detects a light beam projected position. Thus, the inclination is detected (see, for example Japanese Patent Application Publication No. 9-304060). In an inclination detector disclosed in Japanese Patent Application Publication No. 9-304060, light beams from a light source are converted into a parallel pencil. The parallel pencil transmits through a bubble tube and the transmitted light is guided to a light sensor through a lens. The light sensor is a photoelectric transducer having an acceptance surface divided into two or four. A difference in amounts of light received between each of the segmented acceptance surfaces is detected from a difference between outputs of each of the acceptance surfaces. Specifically, in a non-inclined state, the bubbles stay at a center portion of the bubble tube. Therefore, amounts of light received by each of the segmented acceptance surfaces are the same and no output difference is produced. However, in an inclined state, a position of the bubbles is shifted to produce difference in amounts of received light between each of the acceptance surfaces. Therefore, based on a difference between outputs detected therefrom, direction and an angle of inclination can be detected.
The inclination detector using electric resistance of an electrolytic solution includes: a common electrode disposed at the center in the horizontal direction of a container containing the electrolytic solution; and external electrodes each disposed at both sides of the common electrode with certain distances therebetween. The inclined inclination detector produces between the external electrodes a difference in sizes of areas which are in contact with the electrolytic solution. Accordingly, a difference is produced between: an electrical resistance between one of the outer electrodes and the common electrode; and an electrical resistance between the other outer electrode and the common electrode. The inclination is detected through detecting the difference in the electric resistances (see, for example Japanese Patent Application Publication No. 9-250923, Japanese Patent Application Publication No. 10-318747, and Japanese Patent Application Publication No. 8-219780). The inclination detector using an electric resistance of an electrolytic solution contains the electrolytic solution in a manner that bubbles are produced in the electrolytic solution container, and thus is a sort of an inclination angle detector using a bubble tube. However, the detection method is different therefrom.
Detection accuracies of both inclination detectors using a bubble tube or electric resistance of an electrolytic solution degrade due to a temperature change. In the inclination detector using a bubble tube, the bubbles in the bubble tube bloats/contracts due to a temperature change to change the detection characteristics of a sensor, thereby degrading the detection accuracy. In the inclination detector using an electric resistance of an electrolytic solution, the electric resistance of the electrolytic solution changes due to a temperature change. Thus, a temperature change produces error in detection result. Therefore, whether either of the methods is used, with conventional inclination detectors, error in detection result is produced due to a temperature change. Thus, correction for temperature is required and the detection accuracy is difficult to be improved.
An inclination detector is known that is free of the problem the conventional inclination detectors have, i.e., detection error due to a temperature change, and thus requires no extra temperature correction unit (see, for example Japanese Patent Application Publication 2008-309660).